class_docstr: Sigmoid activation followed by a sigmoid cross entropy loss.
class_docstr_tok: ["Sigmoid","activation","followed","by","a","sigmoid","cross","entropy","loss","."]
code: def backward(self, inputs, grad_outputs):
      x, t = self.get_retained_inputs()
      (gy,) = grad_outputs
      (gx,) = SigmoidCrossEntropyGrad(
          self.reduce, self.count, self.ignore_mask, t.data
      ).apply((x, gy))
      return gx, None
  
file_path: chainer/chainer/functions/loss/sigmoid_cross_entropy.py
imports: import chainer
  from chainer import backend
  from chainer import function_node
  from chainer.functions.activation import sigmoid
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the SigmoidCrossEntropy obj's underlying member method code with example usage: obj.backward(inputs, grad_outputs) and returns: gx,  None